1. Field of the Invention
This invention relates to microminiature scanning microscopes, such as tunneling microscopes (STMs) and atomic force microscopes, and, more particularly, to microfabricated microscope structures which incorporate a surface to be scanned and a cantilever arm having a scanning tip at the end thereof.
2. Prior Art
Previously, surfaces to be scanned by a STM were positioned opposite the scanning tip by use of precision mechanical adjustment mechanisms.
In a paper entitled "SCANNING TUNNELING MICROSCOPY" by Binnig and Rohrer, the IBM Journal of Research and Development, Vol. 30, No. 4, pages 355-369, July 1986, a scanning tunneling microscope is depicted in FIG. 2 using a piezoelectric tripod. This tripod consists of 3 piezoelectric rods of material joined at a junction; each rod expands and contracts along one of 3 Cartesian coordinate axes. The tip is mounted at the junction of the 3 rods. The tip is brought into proximity of the surface by a rough positioner. Thereafter the piezoelectric tripods are used to scan the tip across the surface to develop an image of that surface.
Such an arrangement is limited in its application because of its relatively great size, making it subject to vibration and thermal drift.
U.S. Patent Application Ser. No. 149,236, filed Jan. 27, 1988, and assigned to the assignee of the present invention describes a microminiature cantilever arm which has a scanning tip mounted at the free end thereof. The cantilever arm is deflected to position the scanning tip with respect to a surface to be scanned. The cantilever is fabricated by integrated circuit fabrication techniques. The cantilever arm is deflected with respect to the surface to be scanned by an actuating mechanism, which is formed by alternating layers of piezoelectric material and conductive layers. The conductive layers can be individually addressed to enable the cantilever arm to move in three independent directions to thereby appropriately position the scanning tip with respect to a surface to be scanned.